Rather, it is the convoluted approach to stack the 1/10th second chrono hand coaxially on top of the regular chronograph seconds. I don't see the usability/value out of it - as some others have pointed out, after a complete revolution of 12 seconds, the usability of the 1/10th hand drastically drops as there's no reliable way to keep track of multiples of 12 seconds. You'd simply just read the regular seconds, and use the 1/10th hand to have a "magnified" view of the 1/10th scale...
The whole idea of stacking the regular chronograph seconds and this 1/10th seconds hand leads to the unnecessarily complex mechanism that we see, which I feel is not closely tied to Patek's philosophy - I believe that Patek's DNA leans toward making useful/legible watches, and creating silent innovations to make them more user-friendly. In this case, I do believe they tried hard to achieve the latter, but I still fail to see the logical purpose of such a complication. Compare this to the travel time, the alarm complications, the linear perpetual, the gear-based annual calendar, the high-tech rattrapante, the repeaters,...
I still think the patents employed are very clever - notably, the clutch hook that locks it to the column wheel is elegantly simple, and may eventually trickle down to future chronograph movements. As for the tiny pinion with fine teeth, my best guesses to the longevity is that the spring force that couples the 1/10th clutch is weaker (the detent spring is independent of the regular clutch below it. Also, the double pendulum safety mechanism increases the resisting force only when the lever is forcefully pushed outwards to prevent unwanted disengage - the mechanism vaguely reminds me of the Chinese Finger Trap toys which pulls harder the more you resist). I also presume that the pinion has to be of a higher hardness material compared to the wheel that engages it.
Regards,
skyeriding